Ann Arbor is a city in the U.S. state of Michigan and the county seat of Washtenaw County. It is the state's seventh largest city with a population of 114,024 as of the 2000 census, of which 36,892 (32%) are college or graduate students. Believed to be named for the spouses of the city's founders and for the stands of trees in the area, Ann Arbor is best known as the location of the main campus of the University of Michigan, which moved from Detroit in 1837.

The city's economy is currently dominated by education, high tech, and biotechnology. Average home prices and property taxes are well above the state and national medians. The city is also known for its political liberalism and its large number of restaurants and performance venues.

Ann Arbor has a Council-manager form of government. The mayor, who is elected every even-numbered year, is the presiding officer of the City Council and has the power to appoint all Council committee members as well as board and commission members, with the approval of the City Council. The mayor of Ann Arbor is John Hieftje (Democrat), who has served in that capacity since the 2000 election. The city council has ten members, two from each of the city's five wards, with the mayor wielding the tie-breaking vote. Council members serve two-year terms; half the council is elected in annual elections. City operations are managed by the City Administrator, who is chosen by the city council.

Ann Arbor is in the 15th Congressional district, and is represented by Representative John Dingell (Democrat). On the state level, the city is in the 18th district in the Michigan Senate. In the Michigan State House of Representatives, the city of Ann Arbor is in the 53rd district, while northeastern Ann Arbor and Ann Arbor Township are in the 52nd district. As the seat of Washtenaw County, the city is the location of the county's trial, civil, and criminal courts. Ann Arbor is the site of a United States district court, whose downtown building also houses a post office.

Left-wing politics have been particularly strong in municipal government since the 1960s – an orientation evident in the passage of strong antidiscrimination ordinances. Voters also approved charter amendments that have lessened the penalties for possession of marijuana (1974), and that aim to protect access to abortion in the city should it ever become illegal in the State of Michigan (1990). In 1974, Kathy Kozachenko's victory in an Ann Arbor city-council race made her the country's first openly homosexual candidate to win public office. In 1975, Ann Arbor became the first U.S. city to use instant-runoff voting for a mayoral race. Adopted through a ballot initiative sponsored by the local Human Rights Party, which feared a splintering of the liberal vote, the process was repealed in 1976 after use in only one election. As of December 2006, Democrats hold the mayorship and all council seats.